The present invention relates to optimizing the performance of an internal combustion engine during a transition between two different combustion modes—for example, a transition between spark ignition (SI) and homogeneous charge compression ignition (HCCI).
In HCCI combustion, an electric discharge (e.g., a spark) is not used to ignite the fuel and air mixture. Instead, well-mixed fuel and air are compressed until ignition occurs simultaneously through the gas/air mixture in an engine cylinder. As a result, fuel savings of up to thirty percent (30%) can be achieved. However, problems arise with using HCCI combustion at increased power levels. As a results, engines have been designed which use HCCI combustion at lower power levels and switch to SI combustion at high power levels.